nes_cpuaddr.py

import os, sys
import qneslib  # qalle's NES library, https://github.com/qalle2/nes-util

# read args
if len(sys.argv) != 3:
    sys.exit(
        "Convert an NES PRG ROM address into possible CPU addresses using "
        "the iNES ROM file (.nes). Args: file address_in_hexadecimal"
    )
(filename, prgAddr) = sys.argv[1:3]

# get file info
if not os.path.isfile(filename):
    sys.exit("File not found.")
try:
    with open(filename, "rb") as handle:
        fileInfo = qneslib.ines_header_decode(handle)
        if fileInfo is None:
            sys.exit("Invalid iNES ROM file.")
except OSError:
    sys.exit("Error reading the file.")

# parse address
try:
    prgAddr = int(prgAddr, 16)
    if not 0 <= prgAddr < fileInfo["prgSize"]:
        raise ValueError
except ValueError:
    sys.exit("Invalid PRG ROM address.")

if not qneslib.is_mapper_known(fileInfo["mapper"]):
    print(
        f"Warning: unknown mapper {fileInfo['mapper']}; assuming 8-KiB PRG "
        "ROM banks.",
        file=sys.stderr
    )

prgBankSize = qneslib.min_prg_bank_size(
    fileInfo["prgSize"], fileInfo["mapper"]
)
print(", ".join(
    f"0x{a:04x}"
    for a in sorted(qneslib.address_prg_to_cpu(prgAddr, prgBankSize))
))